Chemosensory quality and intensity reflected in implicit affective responses

Implicit measurements are indirect and could register emotions elicited by tasting without conscious awareness. While we know that some basic tastes such as sweetness and bitterness are innately liked or disliked, little is known about the affective responses to tactile sensations. It is also underexplored in which way the emotional responses to chemosensory stimuli are affected by the intensity of the stimulus. To address these issues an implicit method based on the Affect Misattribution Procedure using the judgment of trustworthiness to neutral faces, a proxy for valence, was developed using real tastes as primes (instead of pictures). Three different implicit measures were compared in an experiment in which 107 Italian PROP (6-n-propylthiouracil) Medium-Tasters were exposed to bitterness, astringency, and sweetness at weak/moderate and moderate/strong intensity. Samples were presented blind in aqueous solution monadically in triplicate. Participants were asked to taste a sample, then a neutral face was briefly presented on a screen, and participants were asked to indicate if they trusted the face (yes/no) and how much (on a 9-point Scale). Reaction times (RTs) for the yes/no responses were also collected. The data indicated that both taste qualities and intensity level influenced the yes/no trustworthiness judgements as well as the ratings and the reaction times. As expected, sweetness elicited the most positive affective responses and bitterness the most negative. Astringency elicited a positive response (but lower than sweetness) when it was presented at low intensity, while it elicited a more negative response when it was presented at higher intensity, and this effect was particularly evident when this was evaluated with the scale. Faster reaction times were observed for lower intensity stimuli that had been evaluated as positive but also for higher intensity stimuli that had been evaluated as negative. The results of the present study represent an advance in methodologies that tap implicit affective reactions to chemosensory qualities found in foods and beverages and that can be used to study food experience.